Dynamic covalent chemistry is exploited to drive a morphological order-order transition to achieve the controlled release of silica nanoparticles encapsulated within diblock copolymer vesicles in alkaline aqueous solution. More specifically, poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) (PGMA-PHPMA) diblock copolymer vesicles were prepared <i>via</i> polymerization-induced self-assembly (PISA) either in the presence or absence of silica nanoparticles. Addition of 3-aminophenylboronic acid (APBA) to such vesicles at pH ~ 10 results in specific binding of this reagent to some of the pendent <i>cis</i>-diol groups on the PGMA chains to form phenylboronate ester bonds. This leads to a subtle increase in the effective volume fraction of this stabilizer block, which causes a reduction in the packing parameter and hence induces a vesicle-to-worm (or vesicle-to-sphere) morphological transition. The evolution in copolymer morphology was monitored using DLS, rheology and SAXS. Vesicle dissociation enables release of encapsulated silica nanoparticles to be achieved at room temperature and the rate of release can be fine-tuned by varying the solution pH and/or the APBA concentration. Moreover, unlike the end-group ionization-driven transitions previously reported for PGMA-PHPMA vesicles, this new approach enables vesicle dissociation to be achieved (i) in the presence of added salt and (ii) when targeting relatively high degrees of polymerization (DP) for the PHPMA membrane-forming block. In summary, dynamic covalent chemistry offers considerable scope for the design of new stimulus-responsive copolymer vesicles for controlled release of nanoparticles triggered by the binding of specific analytes.

Using dynamic covalent chemistry to drive morphological transitions: Controlled release of encapsulated nanoparticles from block copolymer vesicles

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.